[Boatanchors] RE: [AMRadio] Tower Construction


david knepper collinsradio at adelphia.net
Tue Jun 13 07:33:55 EDT 2006


I appreciate all the email on this subject.

Interestingly, when lightning rods were placed on barns all over this 
country, I cannot recall any barn in our region ever catching on fire 
because of a lightning strike.  I am sure that it did happen in other 
regions, particularly, in the Midwest/   The installation was to run a very 
large conductor cable from the lightning rod to the ground.   There were 
generally two rods on either end of the roof.  I would theorize that a 
lightning strike should be directed to a ground rod placed a few feet from 
the tower rather than to travel under the base of the tower as some have 
suggested.  I am going to ground the tower at the three legs with a copper 
strap and then to a ground rod about 3 feet from the tower.

Also, the Empire State Building and other skyscrapers get struck many times 
during a thunder storm and I wonder if anyone knows if the lightning travels 
through the superstructure or through cables/straps to the base of the 
building and through ground rods.

Thanks

Dave, W3ST
Publisher of the Collins Journal
Secretary to the Collins Radio Association
www.collinsra.com - the CRA Website
Now with PayPal
CRA Nets: 3805 Khz every Monday at 8 PM EST
and 14255 every Saturday at 12 Noon EST
----- Original Message ----- 
From: "Gary Schafer" <garyschafer at comcast.net>
To: "'Stevan A. White'" <w5saw at pathwayz.com>; "'Discussion of AM Radio'" 
<amradio at mailman.qth.net>; <boatanchors at mailman.qth.net>
Sent: Monday, June 12, 2006 10:10 PM
Subject: [Boatanchors] RE: [AMRadio] Tower Construction


> Be careful when giving this advice.
> A UFER ground is a good SUPLEMENTAL ground in a tower base but it should 
> not
> be the only ground. A large area like a floor of a building provides more
> surface for the lightning to dissipate. A tower concrete foundation may 
> not
> be large enough by itself and there is the possibility of poor connections
> inside so that the concrete crack from a lightning strike if it is the 
> only
> ground connection. It is always recommended that ground rods be attached 
> to
> each tower leg in addition.
>
> 73
> Gary  K4FMX
>
>
>
>>
>> DO RUN THE GROUND THROUGH THE CONCRETE!  Take a look at the information 
>> on
>> this site first though.  You may be glad you did.
>>
>> http://www.scott-inc.com/html/ufer.htm
>>
>> Best Regards,
>> Steve White, W5SAW
>> SW Commercial Electronics
>>
>>
>> -----Original Message-----
>> From: Ed Swynar [mailto:gswynar at durham.net]
>> Sent: Saturday, June 10, 2006 2:16 PM
>> To: Discussion of AM Radio; boatanchors at mailman.qth.net
>> Subject: Re: [AMRadio] Tower Construction
>>
>>
>> Hi Dave,
>>
>> I have a 48' tall, tapered, self-supporting "Delhi"-brand tower --- 6
>> sections at 8' long each.
>>
>> The prescribed / manufacturer's recommendation is to bolt a 3' straight
>> formed extention at the base of each leg (total of 3), & to "suspend"
>> these
>> (a temporary wooden "cradle" will do admirably, as the cement sets) in a
>> hole dug 4' square, & 4-1/2' deep --- the cement is to come but a few
>> inches
>> below the bottom legs of the actual tower section.
>>
>> Oh yes --- the bottom 1' of the square hole is to be "belled" outward a
>> foot, or so.
>>
>> The documentation says this is good for heights of up to 64', or 
>> so...I've
>> never gone beyond 48', & have never, EVER had an ounce of trouble in the
>> two
>> locations that I've had my tower up.
>>
>> BTW, the top of the tower as an old Cornell-Dubelier AR-44 rotator, & a
>> 3-element Hy-Gain TH3 MkIII triband yagi...
>>
>> Use "industrial"-grade coarse cement, & do NOT run any ground leads
>> through
>> the block itself!
>>
>> ~73~ Eddy VE3CUI - VE3XZ
>
>
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